1. Field of the Invention
The present invention relates to a semiconductor light receiving element that can improve wavelength stability.
2. Background Art
FIG. 9 is a sectional view showing a surface incidence resonance photodiode (PD). An n-type multilayer reflective layer 102, an n-type phase adjusting layer 103, an i-type InGaAs absorptive layer 104, a p-type phase adjusting layer 105, and a p-type multilayer reflective layer 106 are sequentially formed on an upper surface of an n-type InP substrate 101. An anode 107 is formed on the p-type multilayer reflective layer 106, and a cathode 108 is formed on a lower surface of the n-type InP substrate 101. The PD is mounted on a pedestal 109.
The n-type multilayer reflective layer 102 and the p-type multilayer reflective layer 106 are layers formed by laminating semiconductor layers having different refractive indices, for example, InP and InGaAsP, and have a function to reflect or transmit light. The n-type phase adjusting layer 103 and the p-type phase adjusting layer 105 have larger band gaps than a band gap of the absorptive layer 104.
Next, the operation of the above-described resonance PD will be briefly described. A reverse bias of about 5 V is applied so that the potential of the anode 107 is lower than the potential of the cathode 108. Light incident from the upper side of the drawing is absorbed in the absorptive layer 104 while reciprocating (resonating) between the n-type multilayer reflective layer 102 and the p-type multilayer reflective layer 106. Pairs of electrons and holes are generated from the absorbed light, and flow to the sides of the cathode 108 and the anode 107, respectively, and are outputted as current. In the resonance PD, since light is absorbed after reciprocating (resonating) many times, high quantum efficiency can be obtained and the resonance Q value of light can be elevated even if the absorptive layer is thinned. The quantum efficiency is the probability of the generation of an electron-hole pair when a photon is incident into the PD.
FIG. 10 is a sectional view showing a backside incidence resonance photodiode (PD). An n-type multilayer reflective layer 102, an n-type phase adjusting layer 103, an i-type InGaAs absorptive layer 104, a p-type phase adjusting layer 105, and a reflective layer 110 are sequentially formed on a lower surface of an n-type InP substrate 101. An anti-reflection film 111 is formed on an upper surface of the n-type InP substrate 101. Light incident from the upper side of the drawing is absorbed in the absorptive layer 104 while reciprocating (resonating) between the n-type multilayer reflective layer 102 and the reflective layer 110 (for example, refer to Japanese Patent Laid-Open No. 2001-308368).